On the first 6 tests of her math class, Jessica got an average score of 79. What does she need on the next test to have an overall average of 82?
Explanation: Let her score on the next test be $x$ The sum of all of her scores is then $6 \cdot 79 + x$ The same sum must also be equal to $7 \cdot 82$ Solve: $x = 7 \cdot 82 - 6 \cdot 79 = 100$.